Method of making lead chlorid.



onfrrnn srn'rns PATENT canton.

EDWIN O. TBARSTOW, E MIDLAND, MICHIGAN, ASSIGNOR U THE DOW CHEMICAL COMPANY, OF MIDLAND, MIC HIGAN, A CORPORATION OF MIGHIGAN.

METHOD OF MAKING LEAD CIHQRID.

No Drawing. 7

To all whom it may con-02M Be it known that I, EDWIN O. Bans'row,

' a citizen of the United States, and a resident of Midland, county of Midland, and State of llllclngan, have invented a new and useful Improvement 111 Methods of Making Lead Chlorid, of which the following is a -ification,'the' principle of the invention herein explained and the-best mode ,ich T have contemplated applying that plan ple, so as to distinguish it from other intuitions.

My present invention, relating as indicated to a method of making lead chlorid (PbCh'), has as its object the provisidn of a process for making such chlorid directly from metallic lead and commercial chlorin.

To the accomplishment of this and related objects said invention, then, consists of the steps hereinafter fully described and particularly pointed out in the claims.

The following description sets forth in 1 detail one mode of carrying out the invention, such'disclosed mode, however, const1-' tuting but one of the various ways in which I the principle of the invention may be used.

As has" been indicated I propose to use chlorm directly in the carrying on of my improied process, and to this end make a. solution of the chlorin in water by bringing the gas into contact with the water, pref- -into water), is charged, and through which the chlorin water, obtained as above, 'is ru n. ll is desirable that provision be made in such tank for prolonged and thorough contact between iluchlorin water and the lead, aiid with 'lhis in \"llfW l'hd tank may be partitioned in a 43;: manner, or by other equivalent de\'i:. a long path of How scs'lllwl for the chlorin water. The lead chl rid. that is formed by the reaction of the chlorlu'iu such water with the metal,

being! sparingly solub e. passe nto solution,

Specification of Iietters Patent. Patented Feb, 21, 1911, Application filed August 12, 1910; Serial momma.

so that one to two per cent. (1% to 2%) I arsenate, sodium carbonate 'or sodium'arsenate, respectively, would be addedrdire'ctly to such solution. If, l1owever,.the 'cblorid-. is

the product sought, it-will be desirable to.

obtain such chlorid in crystallineiorm. A

further step in the present proce ss willae-' cordingly be the rccoveryof the chlorid in this form from the solution resulting from the above described reaction. To obtain such desired crystalline product, I take advantage of the fact that the solubility of leadchlorid in water is lowered by cooling; the process, then, is conducted in the following manner, the cycle ot operations being repeated as often as desired until enough of the chlorid has been separated out; A cool saturated lead chlorid solution,,such as would flow from the leach tank above referred to, is warmed or heated andthen treated with, more chlorin, it being immate' rial in which order the two operations of heating and chlorinatnv are conducted. The resulting lead chlorid solution with lts content of free chlorin is then passed through a tank filled with metallic lead,

wherein the free chlorin unites with the metal to form additional lead chlorid. The latter going into solution increases the percentage of such chlorid so that when the solution is cooled again, part ofthe chlo- The clear, cool, satrid will crystallize out. urated lead chlorid solution is next sepa* rated from the crystals, as by decantation, and then reheated and rechlorinated, and is again subjected to the same cycle of operation to obtain a further quantity of crystals.

l have found that the action of the dissolved chlorin on the lead is greatly accelerated if pieces of carbon or graphite be mixed with the lead in the leaching tank. This action of the carbon in accelerating the solution of the lead would seem to' be an electro-clicmical one, although no experin'iental research has been conducted by me to establislnthat opinion. A. convenient form of carbon for this purpose is obtainable, as scrap graphitized carbon, which may be crushed or not as desired. By the satisfactorily with a. far smaller weight of lead in the solution tank than as though no 5 carbon were used. This feature is of importance because thereby less capital requires to be'tied up in process, while a closer.

clean-up at the end of a run is likewise obtainable. IVhile, as indicated, it.- is pre- 1" ferred to use graphite carbon, other forms of carbon such as-coke gas carbon and the like may be used. By the process which I have thus describe it will be seen that the direct production of I lead chlorid from the metal and chlorin is rendered possible, a result which so far as I am aware has never heretofore been obtained in commercial practice. The success of the present method I attribute in part to the elimination of the action of the air by first absorbing the chlorin in water and then treating the lead in the dissolved chlorin in the substantial absence of the air ;-for I have found that if it be attempted to produce the chlorid by treating metallic lead with water and commercial chlorin s1- multaneously, as by passing the gas into an absorption tower, or other chamber, packed with lead, over which water is caused to trickle, lead peroxid will also be formed,

presumably because of the presence of an in the gas, and, this peroxid being Insoluble, it will form a protective coating over the lead so as to prevent, or at least seriously hinder further action of the chlorin thereon.

Other modes of applying the principle of my invention may be employed instead of the one explained, change being made as regards the process herein disclosed, pro- 0 ride'd the step or steps stated by any one of the following claims or the equivalent of such stated step or steps be employed. 0

I therefore particularly point out and distinctly claim as my invention 1. In a process of making lead chlorid, the step which consists in treating metallic lead withchlorin in solution.

2. In a process of making lead chlorid, the step which consists in treating finely divlded metallic lead with chlorin in solution. 7

3. In a process of making lead chlorid,the step which consists 'in treating granulated metallic lead with chlorin water.

4. In a process of making lead chlorid, the

' step which consists in treating metallic lead a ,with a solution of chlorin in the presence bf carbon.

v 5. In a process of making lead chlorid, the step which consists in treating finely divided metallic lead, intermingled with carbon, with chlorin water. 7

(3. In a process of making lead chlor1d,the steps which consist in absorbing chlorin in water, and then bringing the chlorin water thus made into contact with metallic lead.

1 T. Iita process of making lead chlorid, the i use of such carbon I find it possible to work 1 steps which consist. in absorbing chlorin in water, and then bringing the chlorin water thus made into prolonged contact with metallic lead his finely divided state.

S. In a process of making lead chlorid, the steps which consist in absorbing chlorin 1n water, and then brmgmgthe Cl'llOIlD water thus made into prolonged contact with granulated lead intermingled with carbon.

' 9. In a process of making lead chlorid,the steps which consist in absorbing commercial chlorin in water, so as to eliminate any air, and thenv bringing the chlorin water thus made into contact with granulated lead intermingled with pieces of graphite.

10. In a process of making lead chlorid, the steps which consist in absorbing chlorin in a solution of lead chlorid, bringing the resulting solution into contact with metalliclead, and then cooling thesolution until a put-ion of the lead chlorid crystallizes out.

1 t. In a process of making lead chlorid,

the steps which consist in warming :1 solution of lead chlorid and'absorbing chlorin iherein, bringing the resulting solution into contact with metallic lead, and then coolin the. solution until the additional lead chlorid, formed by the, action of such absorbed chlorin on the lead, crystallizes out.

12. In a process of making lead chlorid, the steps which consist in warming :1 solution of lead chlorid and absorbing chlorin.

therein, bringing the resulting solution into contact with metallic lead, and then cooling the solution until a portion oft-he lead chlorid crystallizes out; and then repeating the preceding steps with the residual solution.

13. In a process of making lead chlorid, the steps which consistin treating metallic lead with chiorin water, absorbing chlorin in the solution of lead chlorid thus obtained, bringing the resulting solution in contact with metallic lead, and then cooling the so lution until a portion of the lead chlorid crystallizes out. 1

14. In a process of making lead chlorid, the steps which consist in treating finely divided lead with chlorin water, absorbing chlorin in the solution of lead chlorid thus obtained, warming the resulting solution and absorbing chlorin therein, bringing the resulting solution into contact with metallic lead, and then cooling the solution until the additional lead chlorid, formed by the action of such absorbed chlorin on the lead, crystallizes out.

15. In a process of making lead chlorid, th steps which consist in absorbing chlorin in a solution of lead chlorid, bringing the resulting solution into contact with metallic lead in the presence of carbon, and then cooling the solution until a portion of the lead chlorid crystallizes out.

16. In a process of making lead chlorid,

the steps which consistin Warming a solution of lead chlorid and absorbing chlorin therein, bringing the resulting solution into contact with metallic lead nd carbon, and then cooling the sol ..tion until the additional lead chlorid, formed by the action of such absorbed chlorin on the lead, crystallizes out.

-17.'In a process of making solid lead chlorid, the steps which consist in warming a solution of lead chlorid and absorbing chlorin therein, bringing the resulting solution into contact with metallic lead intermingled with carbon, and then cooling the solution until a portion of the lead chlorid crystallizes out; and then repeating the preceding step with the residual solution.

18. In a process of making solid vlead chlorid, the ste s which consist in treating metallic lead with chlorin water, absorbing chlorin in the solution of lead chlorid thus obtained, bringing the resulting solution in contact with metallic lead intermingled with carbon, and then cooling the solution until,

a portion of the lead chloricl crystallizes out. i

19. In a process of making solid lead I action of such absorbed chlorin on the lead crystallizes out.

- EDWIN O. BARSTOW. Attested by- LEO VJ. Lows,

THos. GaIsWOLn,Jr.

Signed by me this 8th day of August, 

